How many miles are in a triathlon?

How many miles do you run in a triathlon? Bike? and Swim?
a sprint triathlon?

Above answer is correct for the Ironman distance.
There are many shorter ones. From a Half Ironman.
Olympic distance is 1500M swim, 40K bike and 10K run.
Shorter distances are considered a sprint Triathlon. There are a few standards, but many distances will be set by what the course will allow.